White rose-bay-Rhododendron albiflorum-Poisonous plant-Andromedotoxins

White rose-bay

General poisoning notes:

White rose-bay (Rhododendron albiflorum) is a native shrub found in southwestern British Columbia. This plant is toxic to sheep, although rare cases of cattle poisoning may occur. The plant contains andromedotoxins (grayanotoxins) that can cause sickness and death after they are ingested by animals (Kingsbury 1964, Looman et al. 1983).

Description:

Shrubs, to 2.5 m, rhizomatous. Stems: bark ± smooth to furrowed; twigs multicellular eglandular-hairy (hairs un-branched) and unicellular-hairy. Leaves deciduous; petiole multicellular eglandular- and stipitate-glandular-hairy and unicellular-hairy; blade narrowly elliptic or ovate to obovate, 2-9 × 0.8-3 cm, thin, membranous to chartaceous, margins minutely serrate, plane, ciliate when young, eglandular- and stipitate-glandular-hairy, apex acute to ± rounded, surfaces scattered eglandular-hairy, ± glabrescent. Floral bud scales stipitate-glandular- and eglandular-hairy abaxially, margins stipitate-glandular-hairy. Inflorescences lateral (axillary, i.e., above leaf scars, spaced along shoots of previous year), fasciculate, 1-2-flowered; bracts similar to bud scales. Pedicels to 9-15 mm, eglandular- and stipitate-glandular-hairy. Flowers ± radially symmetric, opening soon after (and borne below) expanded leaves, pendulous, very fragrant (similar to vanilla and jasmine); calyx lobes 5-17 mm, eglandular- and stipitate-glandular-hairy, margins glandular-hairy; corolla white, rarely marked with yellow, bowl-shaped, 9-22 mm, minutely unicellular-hairy or glabrous on outer surface, petals connate, lobes 6-15 mm, tube expanding into lobes, 3-9 mm; stamens 9(-12), included, ± unequal, 5.5-14 mm. Capsules borne on erect pedicels, 6-8 × 5-6 mm, stipitate-glandular-, eglandular-, and unicellular-hairy. Seeds with distinct tails; testa closely appressed. 2n = 26.

Nomenclature:

Scientific Name: Rhododendron albiflorum Lam.

Synonym name (s): Azaleastrum albiflorum (Hooker) Rydberg; Rhododendron albiflorum var. warrenii (A. Nelson) M. A. Lane

Vernacular name(s): white rose-bay, white rhododendron

Scientific family name: Ericaceae

Vernacular family name: heath

Geographic Information:

British Columbia, Alberta.

Toxic parts:

Leaves.

Notes on Toxic plant chemicals:

Andromedotoxins (including grayanotoxin I) are toxic diterpenoids that are present in all the poisonous members of the heath family, Ericaceae (Cooper and Johnson 1984).

Toxic plant chemicals:

Andromedotoxins.

Chemical diagram(s) are courtesy of Ruth McDiarmid, Biochemistry Technician, Kamloops Range Station, Agriculture and Agri-Food Canada, Kamploops, British Columbia, Canada.

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Cattle

General symptoms of poisoning:

Anorexia, death, vomiting, nasal discharge, salivation, weakness.

Notes on poisoning:

Cattle are not poisoned as often as sheep because of the bitter taste of the leaves. Symptoms of ingestion may include initial anorexia, salivation, and dullness. Vomiting may be accompanied by bloat. Abdominal pain and nasal discharge occur. In severe cases, death may result (Kingsbury 1964).

Sheep

General symptoms of poisoning:

Convulsions, death, nasal discharge, paralysis, salivation.

Notes on poisoning:

The palatability of the leaves is low. However, ingesting the leaves causes symptoms, including salivation, nasal discharge, convulsions, paralysis of the limbs, and weakness. In severe cases, death can occur after a period of coma (Looman et al. 1983).